5892-39-7Relevant academic research and scientific papers
CLERODANE AND LABDANE DITERPINOIDS FROM BACCHARIS SPECIES
Bohlmann, Ferdinand,Banerjee, Shanta,Jakupovic, Jasmin,Grenz, Michael,Misra, Laxmi N.,et al.
, p. 511 - 516 (1985)
Key Word Index - Baccharis spp; Compositae; diterpenes; clerodanes; labdanes; nor-diterpene. The investigation of eight Baccharis species afforded, in addition to known compounds, five clerodanes, three labdane derivatives and a nor-diterpene as well as one hydroperoxide derived from 4α-hydroxygermacra-1(10),5-diene.The structures were elucidated by spectroscopic methods.The structures of esters isolated previously from B. cassinaefolia have to be revised.Chemotaxonomic aspects are discussed briefly.
Site-selective synthesis of acacetin and genkwanin through lipase-catalyzed deacetylation of apigenin 5,7-diacetate and subsequent methylation
Fujita, Rie,Hanaya, Kengo,Higashibayashi, Shuhei,Mandal, Susanta,Shoji, Mitsuru,Sugai, Takeshi
, p. 638 - 648 (2019/07/31)
Candida antarctica lipase B-catalyzed deacetylation proceeded with high site-selectivity on the C-4′ acetyl group in apigenin triacetate to give apigenin 5,7-diacetate. Methylation of the liberated hydroxy group with the combination of trimethyloxonium tetrafluoroborate (Meerwein reagent) and 1,8-bis(dimethylamino)naphthalene (proton sponge) in CH2Cl2 proceeded in a quantitative manner to give the product methylated at the C-4′ hydroxy group (acacetin 5,7-diacetate). Even with the same precursor, a different methylation product at the C-7 hydroxy group (genkwanin 4′,5-diacetate) was obtained in 86% yield by applying iodomethane and Cs2CO3 in dimethyl sulfoxide (DMSO). The methylated products were deprotected to form acacetin and genkwanin. We inferred that the latter unexpected methylation was ascribable to the intermolecular migration of an acetyl group from C-7 to C-4′. DFT calculations indicated that the C-7 phenoxide ion was 12.6 kJ/mol more stable than the initially formed C-4′ phenoxide ion.
Synthesis of acacetin and resveratrol 3,5-di-O-β-glucopyranoside using lipase-catalyzed regioselective deacetylation of polyphenol glycoside peracetates as the key step
Hanamura, Shun,Hanaya, Kengo,Shoji, Mitsuru,Sugai, Takeshi
, p. 19 - 26 (2016/03/30)
Acacetin and resveratrol 3,5-di-O-β-glucopyranoside were synthesized from naturally abundant naringin and piceid in 65% and 62% overall yield, respectively. The key steps were the regioselective deacetylation of the peracetates of the glycosylated forms with Candida antarctica lipase B (Novozym 435) and Burkholderia cepacia lipase (Amano PS-IM). Deacetylation occurred exclusively at the least hindered position of the aromatic moieties and all acetyl groups in the sugar side chain remained intact. This excellent selectivity enabled regiospecific transformation of the liberated phenolic hydroxy groups, resulting in efficient synthesis of the target molecules.
